Snowblowe belt problem

I have a Sears two stage snow blower. It's maybe ten years old and has a new engine. It works fine with one exception. The belt to the augur will slip off the flywheel for no apparent reason. I was ploughing today. I got 80% of the job done (about 40 minutes work) when suddenly, no augur. You open it up and the belt has jumped off the drive wheel. This has happened several times before. So far as I can see, the tension on the pulleys and the little guides are set properly. Running it with the cowling off, everything seems to work just fine. In fact when I got the belt back in place...no easy task with bare fingers in 5 degree weather...it ran just fine for the balance of the job. But I know it will happen again. Any ideas? ds
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There could be any number of reason and causes, misaligned pulleys, a non-obvious failure in the belt or stretch, loose nut behind the controls <grin> The most obvious thing I would do is replace the belt, probably under $15, after that you've got to check bearings on the pulley shafts. They could be worn just enough so that under strain they allow enough shaft movement to throw the belt. I find that if I try to move to much snow at once that's when the older snow throwers act up. But you don't need me telling you how to use your machine.
Dave
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Most Snowblowers I've seen have a wire belt guide mounted on the engine to prevent the belt from jumping. Did this get lost when you changed the engine?
Ante
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